A method for extending steering wheel angle based on motor position sensor

Abstract

This invention belongs to the field of automotive manufacturing technology and relates to a method for extending the steering wheel angle based on a motor position sensor. After determining the steering wheel angle, a torque angle sensor (TAS) is selected to measure the current steering wheel angle, or the current steering wheel angle can be calculated using the TAS, the motor position sensor, and the torsion bar deformation angle. This allows the actual steering wheel angle to be calculated using the motor position sensor in conjunction with the TAS when the steering wheel angle exceeds the measurable range of the TAS. The motor position sensor is an existing signal in the EPS system, requiring no additional components and saving development costs. Furthermore, this method is adaptable to different vehicle models, including passenger cars and commercial vehicles, improving software compatibility.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of automobile manufacturing and relates to a method for extending steering wheel angle based on motor position sensor. BACKGROUND

[0002] With the gradual maturity of electric power steering system (EPS) in the field of passenger cars, EPS is also rapidly developing in the field of commercial vehicles. In EPS, one signal is very important, that is, the steering wheel angle signal. The steering wheel angle signal not only needs to be used by itself, but also needs to be communicated to other modules of the vehicle. Therefore, the importance of this signal can be seen. At present, most of the torque angle sensors (TAS) provided by manufacturers on the market are small angle range, for example, within ±740° range, that is, to meet the steering wheel rotation range of passenger cars. Since the steering wheel rotation angle of commercial vehicles is larger and often exceeds ±740° range, the existing torque angle sensor (TAS) cannot measure when it exceeds ±740° range. Therefore, if the same type of sensor is used on commercial vehicles to normally steer the steering wheel, it will inevitably affect the steering function.

[0003] The existing commercial vehicle electric power steering system uses Hella small angle torque angle sensor to measure the steering wheel angle. Since the measurement range of this small angle sensor is small, on the one hand, it cannot meet the requirement of measuring the large angle steering wheel angle of commercial vehicles; on the other hand, if a large angle sensor is replaced, since the software algorithms of the two types of sensors are incompatible, not only the software complexity will be increased, but also the development cost will be increased.

[0004] Therefore, in order to solve the problems that the measurement angle range of the existing small angle torque angle sensor cannot meet the requirement of the steering system of commercial vehicles and the software of the existing large angle torque angle sensor and small angle sensor is incompatible and expensive, a method for extending the steering wheel angle of commercial vehicles based on the existing small angle torque angle sensor is needed. SUMMARY

[0005] The technical solution adopted by the application to solve the technical problems is: a method for extending steering wheel angle based on motor position sensor, comprising the following steps:

[0006] Step one: after the vehicle is powered on, in the software initialization stage, the related information of the steering wheel is read from the memory, and after successful reading, the steering wheel angle is judged whether it is in the extension state in combination with the measurement angle of the current torque angle sensor TAS, that is, whether the steering wheel angle is within the measurement range of the torque angle sensor TAS is determined.

[0007] Step two: when the steering wheel angle is determined to be in the non-extended state, i.e. the steering wheel angle is within the measurement range of the torque angle sensor TAS, then jump to step three; when the steering wheel angle is determined to be in the extended state, i.e. the steering wheel angle is not within the measurement range of the torque angle sensor TAS, then jump to step four;

[0008] Step three: measure the current steering wheel angle by the torque angle sensor TAS, and then go to step five;

[0009] Step four: calculate the current steering wheel angle by the torque angle sensor TAS, the motor position sensor and the torsion bar deformation angle, and then go to step five;

[0010] Step five: store the current steering wheel angle, or when the ignition signal is detected to be off, the ECU immediately stores the angle-related information and a flag bit, and waits to be read after the next power-on.

[0011] Preferably, in step three, when the torque angle sensor TAS measures that the current steering wheel angle exceeds the measurement range, then go to step four.

[0012] Preferably, in step four, when the torque angle sensor TAS, the motor position sensor and the torsion bar deformation angle jointly calculate the current steering wheel angle, and the current steering wheel angle is not more than the measurement range of the torque angle sensor TAS, then go to step three.

[0013] Preferably, in step four, the calculation method of the torque angle sensor TAS, the motor position sensor and the torsion bar deformation angle jointly calculating the current steering wheel angle is as follows:

[0014] θ diff = (θ - θ0) * k (1)

[0015] In formula (1):

[0016] θ diff is the motor rotation angle in the extended state, in °;

[0017] θ is the motor position;

[0018] θ0 is the motor position at the moment of entering the extended state;

[0019] k is the coefficient for calculating the motor angle to the steering wheel angle, which is taken as 2.25 here;

[0020] θ t = T ÷ k (2)

[0021] In formula (2):

[0022] θ t is the torsion bar deformation angle, in °;

[0023] T is the steering wheel torque size, unit N.m;

[0024] k is the torsion bar stiffness coefficient;

[0025] θ steering = θ tas + θ diff + θ t (3)

[0026] In formula (3):

[0027] θ steering is the steering wheel angle, unit °;

[0028] θ tas is the tas sensor angle, unit °;

[0029] θ diff is the motor rotation angle in the extended state, unit °;

[0030] θ t is the torsion bar deformation angle, unit °.

[0031] The beneficial effects of the present application are:

[0032] The present application selects the torque angle sensor TAS to measure the current steering wheel angle after determining the steering wheel angle, or selects the torque angle sensor TAS, motor position sensor and torsion bar deformation angle to jointly calculate the current steering wheel angle; so that when the steering wheel angle exceeds the measurable range of TAS, the actual angle of the current steering wheel is calculated by cooperating the motor position sensor with TAS, the motor position sensor is the original signal of the EPS system, no additional devices are added, and the development cost is saved. On the other hand, the method of the present application can be adapted to different vehicle models, passenger cars or commercial vehicles, and improve software compatibility. BRIEF DESCRIPTION OF DRAWINGS

[0033] Fig. 1 It is a flow chart of a method for extending the steering wheel angle based on the motor position sensor;

[0034] Fig. 2 It is a mechanical connection schematic diagram;

[0035] Fig. 3 It is an embodiment test result graph. DETAILED DESCRIPTION

[0036] With reference to the drawings of the embodiments of the present application, the related art in the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0037] Reference Figs. 1-3 A method for extending the steering wheel angle based on the motor position sensor, comprising:

[0038] Step one: after the vehicle is powered on, the related information of the steering wheel stored in the memory is read in the software initialization stage. After successful reading, whether the steering wheel angle is in the extended state is judged in combination with the measured angle of the current torque angle sensor TAS, that is, whether the steering wheel angle is within the measurement range of the torque angle sensor TAS is determined.

[0039] Step two: when it is determined that the steering wheel angle is in the non-extended state, that is, the steering wheel angle is within the measurement range of the torque angle sensor TAS, jump to step three; when it is determined that the steering wheel angle is in the extended state, that is, the steering wheel angle is not within the measurement range of the torque angle sensor TAS, jump to step four.

[0040] Step three: the current steering wheel angle is measured by the torque angle sensor TAS, and then step five is turned to.

[0041] Step four: the current steering wheel angle is calculated by the torque angle sensor TAS, the motor position sensor and the torsion bar deformation angle, and then step five is turned to.

[0042] Step five: the current steering wheel angle is stored, or when the ignition signal is detected to be off, the ECU immediately stores the angle related information and the flag bit, and waits for the next power-on to read and use.

[0043] Further, in step three, when the torque angle sensor TAS measures that the current steering wheel angle exceeds the measurement range, step four is turned to.

[0044] Further, in step four, after the torque angle sensor TAS, the motor position sensor and the torsion bar deformation angle jointly calculate the current steering wheel angle, if the current steering wheel angle does not exceed the measurement range of the torque angle sensor TAS, step three is turned to.

[0045] Further, in step four, the calculation method of the torque angle sensor TAS, the motor position sensor and the torsion bar deformation angle for jointly calculating the current steering wheel angle is:

[0046] θ diff =(θ-θ0)*k (1)

[0047] θ in formula (1) is the motor angle in the extended state, in °;

[0048] θ diff is the motor angle in the extended state, in °;

[0049] θ is the motor position;

[0050] θ0 is the motor position at the time of entering the extended state;

[0051] k is the coefficient for calculating the motor angle to the steering wheel angle, which is taken as 2.25 here;

[0052] θ t = T ÷ k (2)

[0053] θ in formula (2) is the steering wheel angle, in °;

[0054] θ t is the steering wheel angle, in °;

[0055] T is the steering wheel torque, in N.m;

[0056] k is the torsion bar stiffness coefficient;

[0057] θ steering = θ tas + θ diff + θ t (3)

[0058] θ in formula (3) is the steering wheel angle, in °;

[0059] θ steering is the steering wheel angle, in °;

[0060] θ tas is the tas sensor angle, in °;

[0061] θ diff is the motor angle in the extended state, in °;

[0062] θ t is the torsion bar deformation angle, in °.

[0063] Embodiment

[0064] In this embodiment, the sensors needed to be used are the TAS sensor and the motor position sensor. According to the mechanical mechanism composition, the connection path from the vehicle steering wheel to the motor signal is as follows:

[0065] Motor shaft -> worm -> turbine -> output shaft -> torsion bar -> input shaft -> steering wheel

[0066] For example, Fig. 2The EPS motor mechanical structure and signal connection diagram is shown. The steering wheel is connected to the torque sensor through the input shaft to measure the steering wheel angle and steering wheel torque. The measurement range is ±740°. Then it is connected to the output shaft through the torsion bar and then connected to the motor shaft through the reduction mechanism. The entire connection system can be considered as hard connection except the torsion bar which is a flexible member. That is, the steering wheel angle can be indirectly calculated by the motor rotation angle.

[0067] As shown in Fig. 1 , after the vehicle is powered on, the software initialization stage first reads the stored steering wheel related information from the memory. After successful reading, it combines the current TAS measurement angle to determine whether the steering wheel angle is in the extended state,

[0068] The software calculation jumps to the corresponding state to calculate the steering wheel angle.

[0069] When the ignition signal is detected to be off, the ECU will immediately store the angle related information and flag bit. Wait for the next power on to read and use. Table 1 below shows the storage variable description:

[0070]

[0071] Table 1 as shown in Fig. 1 , the specific algorithm implementation code is as follows:

[0072] The interface variable definition is shown in Table 2:

[0073]

[0074]

[0075] The function function implementation is as follows:

[0076]

[0077]

[0078]

[0079] The function test result is shown in Fig. 3 , the dashed line is the TAS measurement angle, and the solid line is the steering wheel angle. The line discontinuity in the figure is that the controller enters the power off state. In order to test whether the steering wheel angle can be correctly recognized after power on, it can be seen that the test result meets the design requirements.

[0080] In summary, the present application selects the torque angle sensor TAS to measure the current steering wheel angle after determining the steering wheel angle, or selects the torque angle sensor TAS, the motor position sensor and the torsion bar deformation angle to jointly calculate the current steering wheel angle; so that when the steering wheel angle exceeds the measurable range of the TAS, the motor position sensor and the TAS are used to calculate the actual angle of the current steering wheel, the motor position sensor is the original signal of the EPS system, no additional devices are needed, and the development cost is saved; on the other hand, the method of the present application can be adapted to different vehicle models, passenger cars or commercial vehicles, and the software compatibility is improved, so the present application has a wide application prospect.

[0081] It should be emphasized that: the above is only the preferred embodiment of the present application, not any form of limitation on the present application, any simple modification, equivalent change and modification of the above embodiment according to the technical essence of the present application still belongs to the scope of the technical scheme of the present application.

Claims

1. A method for extending the steering wheel angle based on a motor position sensor, characterized in that, Includes the following steps: Step 1: After the vehicle is powered on, during the software initialization phase, the relevant information of the steering wheel stored in the memory is read first. After successful reading, the steering wheel angle is determined by combining the measured angle of the torque angle sensor TAS to determine whether the steering wheel angle is in the extended state, that is, whether the steering wheel angle is within the measurement range of the torque angle sensor TAS. Step 2: When it is determined that the steering wheel angle is in a non-extended state, that is, the steering wheel angle is within the measurement range of the torque angle sensor TAS, then proceed to step 3; When the steering wheel angle is determined to be in an extended state, that is, the steering wheel angle is not within the measurement range of the torque angle sensor TAS, then proceed to step four. Step 3: Measure the current steering wheel angle using the torque angle sensor (TAS), then proceed to Step 5; Step 4: Calculate the current steering wheel angle using the torque angle sensor (TAS), motor position sensor, and torsion bar deformation angle, then proceed to Step 5; Step 5: Store the current steering wheel angle, or when the ignition signal is detected to be off, the ECU immediately stores the angle-related information and flags, waiting to be read and used after the next power-on; The calculation method for calculating the current steering wheel angle using the torque angle sensor (TAS), motor position sensor, and torsion bar deformation angle in step four is as follows: （1） In formula (1): θ diff The angle of rotation of the motor in the extended state is expressed in degrees. θ represents the motor position; θ0 is the motor position at the moment of entering the extended state; k is a coefficient used to calculate the angle from the motor angle to the steering wheel angle; here, it is set to 2.

25. （2） In formula (2): θ t The angle of torsion bar deformation is expressed in degrees (°). T represents the steering wheel torque, in Nm. k is the stiffness coefficient of the torsion bar; （3） In formula (3): θ steering Steering wheel angle, in degrees; θ tas The angle of the tas sensor is in degrees. θ diff The angle of rotation of the motor in the extended state is expressed in degrees. θ t The value represents the torsion bar deformation angle, in degrees (°).

2. The method for extending the steering wheel angle based on a motor position sensor according to claim 1, characterized in that, In step three, if the torque angle sensor TAS measures that the current steering wheel angle exceeds the measurement range, then proceed to step four.

3. The method for extending the steering wheel angle based on a motor position sensor according to claim 1, characterized in that, In step four, if the torque angle sensor TAS, motor position sensor, and torsion bar deformation angle jointly calculate the current steering wheel angle and find that the current steering wheel angle does not exceed the measurement range of the torque angle sensor TAS, then proceed to step three.

Images